1. Technical Field
The present disclosure relates to nonaqueous electrolyte batteries, particularly to lithium ion secondary batteries.
2. Related Art
Nonaqueous electrolyte batteries have been put into practical use as batteries for vehicles including hybrid vehicles and electric vehicles. Lithium ion secondary batteries have been used as such on-vehicle batteries. Lithium ion secondary batteries have been required to have various characteristics: output characteristic, energy density, capacity, lifetime, and high-temperature stability. In particular, various improvements for the electrolyte solution have been attempted in order to enhance the battery life (cycle characteristic and preservation characteristic).
For example, JP-A-11-283667 has suggested the battery including the electrolyte solution containing propylene carbonate and vinylene carbonate. This electrolyte solution is employed for the purpose of preventing the crystal structure of the lithium manganate composite oxide contained in the positive electrode active material from being destroyed when the battery is preserved under high temperature. In the example according to JP-A-11-283667, the lithium manganese composite oxide is used as the positive electrode active material and the nonaqueous electrolyte solution containing propylene carbonate (or ethylene carbonate), vinylene carbonate, and diethyl carbonate is used as the electrolyte solution. From the viewpoint of improving the cycle lifetime, for example, using a lithium nickel composite oxide as the positive electrode active material has been attempted.